Ok, this post is full of stereotypes that I don't even know if I should dignify this with a response, but alas I will
First, despite what a bunch of morons with their own various reasons would have you believe, the word "urban" is not synoynmous with "minorities".
Urban is simply a description given to a certain type of organization of society, namely that of the focus city of any given metropolitan area.
And for the belief that rural soldiers would always be European-American, to this I say
Macon County, AL approximately 24,000 residents. 85% black
Issaquena County, MS approximately 2,200. 62% black
And, if you want to really get rural
Kenedy County, TX, approximately 400 people, 79% hispanic.
As an aside, since you seem to be fluent regarding demography, is there a major urban area aside from Salt Lake City where the average young man is likely to be white?
I only did ten years in the Corps...most of that in the infantry. I can only tell you what I saw, which was white kids join for adventure, most inner city minority kids join to get job skills.